The present invention relates to the field of optics, and more particularly to a specific apparatus and process for three dimensional (3-D) image presentation.
Workers in the photographic and optics fields have long sought practical methods and systems for presenting images in 3-D to viewers, including 3-D presentations of video screen images, transparency images or printed images.
An object of this invention is to provide a display apparatus and method that simulates a surprisingly realistic 3-D effect when viewing a normally flat two dimensional (2-D) image. In accordance with the invention, any 2-D image may be so viewed, including photographic images, video or computer screens, drawings, paintings or sketches. The images may be still or motion, black and white or colored, printed or broadcast, complex or sketchy.
A further object of this invention is to provide 3-D presentations of images recorded, processed, and presented using conventional 2-D means. For example, conventional (2-D) TV broadcasts are not affected in any way while viewers, equipped with an optically active device of the invention, will experience realistic depth of field image viewing. Thus, no special processing of the image or broadcast signal is required--no "3-D dedicated" broadcast is required (which may be distorted to the naked eye).
The same advantage of "undedicated" image presentation also applies to any image distribution means such as recorded video signals (i.e. from video cassette recordings), computer generated graphics (i.e., computer games), printed or published images, motion picture viewing, single or mass produced slides, postcards, photographs, etc.
A further and related object of this invention is to provide a realistic 3-D view of 2-D images without the need for "stereo glasses", usually required to view conventional 3-D stereo photographs. Such glasses provide a means to assure that each eye only sees its respective image from two photographs taken from slightly displaced points of view. The isolation of each eye can be by, for example, alternating polarization, color filtration or by alternate time-divided occlusion of each eye's vision, in timing with a shifting of images in a moving picture. Viewers not equipped with such glasses see a blurred or double image. In addition, some individuals have difficulty fusing the separate images, failing to experience an illusion of depth, or experience headaches with extended viewing. The present invention described below provides some degree of three dimensional effect even with only one eye viewing (however, both eyes viewing in coordination provides the best effect).
Modifications allowing the elimination of stereo glasses have been described; however, such methods still incorporate the principle of two or more displaced images. One approach has been the use of lenticular screens. Such screens consist of one or more sheets of connected thin cylindrical lenses, usually attached to the surface of specially processed photographic matrices assembled from two or more multiple views. A disadvantage of this approach is that each image must be specially processed; conventional film processing or conventional video display viewing systems are not compatible with these methods. An additional problem with the lenticular approach, as experienced by the viewer, is a "choppy" or "ripple" effect as the viewer shifts his viewing angle.
Another "stereo glasses free" technology is holography. Holographic methods provide a realistic 3-D image. However, as is the problem with the lenticular approach, this technology is not compatible with conventional photographic or video image viewing systems. In addition, holograms are limited to coherent or lased light illumination during the recording phase. Thus, holography cannot record whole light illuminated objects or scenes, but is limited to recording only images of objects placed relatively close to the photosensitive recording substrate. Further, complex set ups and alignments are usually required. For motion or full color holograms, even more complex set ups involving multiple exposures are required; these factors severely limit this approach for most conventional uses.
A still further object of this invention, in a second embodiment, is to provide apparatus and methods for dedicated recording and subsequent reconstruction of 3-D image signal information for transmission, processing or storage.
In the field of 3-D imaging and viewing, Jones U.S. Pat. No. 3,564,987 discloses the use of multiple, stacked cylindrical lenses to form multiple images on a recording medium. The disadvantages of these lenticular approaches have been discussed above. An additional disadvantage of this approach (as well as of conventional stereo photography) is the 3-D effect can only be experienced when the image is directly right-side up or directly up-side down; the depth effect is lost if viewed between these two extremes. Thus, the viewer has no degree of freedom of movement while viewing conventional stereo images. The Jones device does not involve an interferometer effect as in the present invention.
Pictet et al. U.S. Pat. No. 1,503,766 discloses the use of piles of glass in conjunction with the use of a pair of stereo binoculars. The piles of glass are used for the purpose of polarizing light in desired directions. The device disclosed by Pictet would have many of the above-described disadvantages and further includes the disadvantage of requiring a cumbersome pair of viewing lenses for viewing the image.
Denison U.S. Pat. No. 2,238,629 discloses the use of multiple cylindrical lenses in producing a three dimensional image. Separate pictures of the same object are photographed and viewed through separate lens systems in, for example, a stereoscopic camera. Noble U.S. Pat. No. 4,671,625 discloses a device for projecting and viewing an object which appears to float in space. Two convex lenses are used in viewing an image of an object. The image appears to float in space by virtue of the removal of surrounding visual information but is not projected as a three dimensional object.
Other patents in the imaging field include Rodriguez U.S. Pat. No. 2.674,919, Brachet U.S. Pat. No. 3,978,500, Yano U.S. Pat. No. 4,078,854, Nakken U.S. Pat. No. 2,185,221 and Geoffray U.S. Pat. No. 3,731,606.